1. Technical Field
The present invention relates to a correction information calculating device, an image processing apparatus, an image display system, and an image correcting method.
2. Related Art
Generally, as one example of an image display device, a projector is known. Projectors have advantages such as ease of installation and the ability to display of a big screen image. Recently, image display systems displaying one image by using a plurality of projectors have been proposed (for example, see JP-A-2002-72359).
In the image display system disclosed in JP-A-2002-72359, partial images are projected by a plurality of projectors, and one image is displayed as a whole of a plurality of the partial images. By overlapping the edge portions of the partial images adjacent to each other, it is difficult to recognize the joining portions of the partial images. In addition, the geometrical deformation of the partial images on the projection surface is corrected. Accordingly, image distortion is reduced.
According to the image display system disclosed in JP-A-2002-72359, in order to perform geometrical correction of the partial images, the following process is performed. First, a test image including a marker is displayed, and the displayed test image is photographed. Then, correction information representing the correction amount of pixel positions is acquired for each projector based on the correspondence relationship between the position of a marker on image data representing the test image and the position of a marker within a photographed image acquired by photographing the test image. In a case where an image for a viewer (hereinafter, referred to as a content image) is displayed, the image data representing the content image is corrected based on the correction information, and partial images are displayed based on the image data after correction.
In the technology disclosed in JP-A-2002-72359, there is room for improvement for the effort and the time until the correction information is acquired. More specifically, according to the technology disclosed in JP-A-2002-72359, when test images are simultaneously projected from a plurality of projectors, in test images adjacent to each other, markers thereof may overlap each other. In such a case, it is difficult to detect the positions of the markers overlapping each other with high precision. Accordingly, it is difficult to acquire the correction information with high precision.
In order to resolve such disadvantages, for example, a method in which test images are projected by shifting projection timings of the plurality of projectors from one another, and the test image of each projector is individually photographed may be considered. In this method, there is a disadvantage in that the effort and time needed for projecting and photographing the test images increases as the number of the projectors is increased. In addition, there is a case where a photographing device is moved from the previous photographing operation to a next photographing operation. When the photographing device is moved, an error may occur in the position of the marker included in the photographed image. Then, the correction information is calculated under a condition in which the positions of the plurality of partial images are deviated from one another. Distortion or a positional difference occurs in the partial images projected based on the image data that is corrected based on the above-described correction information.